If I perform /ess, then in the chat it looks like a bug. Minor. <command> is not replaced to command name ("ess" in this case).
https://github.com/drtshock/Essentials/blob/2.x/Essentials/src/com/earth2me/essentials/commands/Commandessentials.java#L62

It's not a bug. :)

This is common behaviour that you will find with all commands.

Maybe you did not understand me. @SupaHam

If I type /ess, then I get this response:

But if I try any other command instead of /ess (/call for example), there will be correct name (/call instead of /<command>):